hoffmann



(No Model.) 2 SheetsSheet 1. R. HOFPMANN. GOMMUTATOR BRUSH FOR DYNAMO ELECTRIC MACHINES 0R MOTORS.

Patented Sept. 10, 1889.

N PETERSxFhulc-Lmvographar. Washingmn, D. C.

(No Model.) 7 2 Sheets-Sheet 2.

R. HOPFMANN.

GOMMUTATOR BRUSH FOR DYNAMO ELECTRIC MACHINES OR MOTORS.

No.. 410,896. Patented Sept. 10, 1889 0mm ear-- & 41 3 N PETERS. Photo-Lnhvgmphur. Washington. 0,0.

4o destruction.

g UNITED STATES PATENT QEEICE.

' RUDOLF HOFFMANN, OF ZURICH, ASSIGNOR TO THE MASCHINENFABRIK OERLIKON, OF NEAR ZURICH, S\VITZERLAND.

COMMUTATOR-BRUSH FOR DYNAMO-ELECTRIC MACHINES R MOTORS.

SPECIFICATION forming part of Letters Patent No. 410,896, dated September 10, 1889.

Application filed June 30, 1888= Serial No. 278,614:- (No model.)

To aZZ whom it may concern.-

Be it known that I, RUDOLF HOFFMANN, a citizen of the Republic of Switzerland, residing at Zurich, in the Republic of Switzerland,

5 have invented certain new and useful Improvcn'ients in the Arrangement of Commutator-Brushes for Electromotors and By names, Specially for Motors of Electrical L0- comotives, (which have not been patented to myself or to others with my knowledge or consent in any country,) of which the following is a specification.

This invention relates to brushes for dynamo electric comm utatormachines or I 5 electric motors.

2o generation and that of no generation, and

which will admit of the commutatorbeing revolved in either direction without changing the relative position of the commutatorbrushes; furthermore, to produce a commu- 2 5 tator-brush which shall be simple of construction, eflicient and durable in use, and comparatively inexpensive of production.

Heretofore commutator-brushes have been arranged substantially at right angles to the axis of the commutator and travel over its face in auniform track, thereby speedily wearing a groove therein and rendering its face uneven. l urthermore, where the brushes are so arranged, there is generally seen a lar e amount of s ark 011 the face of a5 a P the coinmutators, indicating a loss of electric energy by its conversion at a point where it is not only unneeded but injurious to the connnutator-brush, in thatit causes its rapid To remedy this defect and to insure even wear of the whole surface of the commutator, I arrange the commutatorbrushes so that they may be adjusted at any angle from a line at right angles to the plane of the axis of the commutator to a line that is approximately parallel with the same, and also raise one or lower the other brush at one and the same time, so that one will be at a point above the plane of the axis and the other below, thus preventing the brushes part of this specificatiomand in which like letters of reference indicate corresponding parts, I have illustrated one form of device with modifications embodying my invention, although the same may be carried into effect in other ways without in the least departing from the spirit thereof.

In the drawings, Figure 1 is a side elevation showing the commutator, the commutatorbrushes, and the hand-lever working over a shunt for operating the same. Fig.2 is a top plan view of the same, the shunt mechanism being detached, showing the position of the commutator-brushes in Fig. 1. Fig. 3 is a side elevation showing another form of commutator to be used when four pole-pieces are employed 011 the machine. Figs. at, 5, 6, 7, S, and 0 are detail views showing the diiferent angles at which the coinimitator-brushes may be adjusted.

Referring to the drawings, A designates the armature of a dynamo'electrio machine, to which this device is attached and which is of ordinary construction. B designates its shaft, on which the cylinder 0 is also mounted. This shaft extends out and is mounted in a suitable box I), so as to prevent the said shaft from runningunevenly. On the sleeve Z) of the bearing-box l) is loosely mounted a yoke D, which is provided with a number of arms (Z and d, the arms (I being designed to support hinged clamps (F, in which the (30111- mutator-brushes E are secured in position against the commutator. The lower arm (1 has pivoted to it a rod F, which extends to and connects with a hand-lever wr, which is pivoted on a shunt or switch board H. The upper part of this switch-board is provided with a number of buttons 7?, to which the wires I from the resistance-box J connect.

As represented in Fig. 1, the hand-lever G is at the zero-point or at the point of no genoration; but should it be desired to start the motor the lever is drawn to one side and, coming in contact with the first button, completes the circuit and starts the motor. When in this position, the brushes are approximately parallel to the plane of the axis of the commutator, as shown in Fig. 5; but by moving the said lever to the point I the brushes will then be in the position shown in Fig. 7 'i. e., one being above and the other below the plane of the axis of the commutator. WVhen the lever is at the point I, the motor will revolve to the right; but should it be desired to reverse its motiont'. e., to cause it to revolve to the leftthe lever is moved to the point I I, when this result will be acco1nplished.

By means of the springs d which are secured to each of the hinged clamps 01 the brushes are always kept in contact with the commutator-cylinder, which thus does away with the necessity of removing them' when they become Worn, as with brushes of ordinary construction. Should it be desired to cause the brushes to bear harder against the commutator-cylinder, it will only be necessary to turn the thumb-nuts d on the springs, which will expand them, and thus increase their tension.

It will be observed that the brushes are set obliquely to the plane of the axis of the commutator cylinder. By this adjustment a much larger surface can be presented to the commutator than if the brushes were held diametrically opposite each other; but should it be desired to adjust them at right angles to the plane of'the axis of the commutator it may be readily done by placing another yoke on the bearing-box, the clamps of which will be arranged for that purpose.

The many advantages of this device are obvious, for while it is not uncommon to change somewhat the position of the commutatorbrushes it is not common to construct a commutator-brush which may be readily adjusted so as to allow the armature to revolve in either direction, and to effect this end without interfering with the wires in any way or changing the commutator-brushes, but by simply moving a hand-lever to effect these changes-that is, to switch the current so as to reverse the motor and change the commutator-brushes at one and the same time.

Having thus fully described my invention, what I claim as new, and desire to secure by Letters Patent is- In a dynamo-electric machine, the combination, with the commutator, the yoke D, seated on the hub 12 ofthe bearing-boxb and provided with the arms d d, the clamps d hinged or pivoted at their outer ends to the ends of the arms d of the yoke, the springs d directly connected at one end to the free ends of the brush-clamps d and at the other end directly connected to the arms d of the yoke, and the brushes E, held in the clamps by suitable screws, of the hand-lever G, pivoted on the switch-board, and the rod F, connecting the arm (1' and the hand-lever, all constructed and arranged substantially as and for the purpose specified.

In testimony whereof I have signed this specification in the presence of two subscribing witnesses.

RUDOLF HOFFMANN.

W'it'n esses:

EMIL BLUM, WILLIAM SCHNEIDER. 

